A lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate. A lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In that instance, a patterning device, which is alternatively referred to as a mask or a reticle, may be used to generate a circuit pattern to be formed on an individual layer of the IC. This pattern can be transferred onto a target portion (e.g. comprising part of, one, or several dies) on a substrate (e.g. a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate. In general, a single substrate will contain a network of adjacent target portions that are successively patterned. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the substrate parallel or anti-parallel to this direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
An apparatus, comprising a debris mitigation system may be provided with a rotatable structure (called a rotating contaminant trap) to capture debris, emanating from an EUV (extreme ultraviolet) radiation source. For example, the source can emit micron-sized or smaller particles, which are unwanted downstream in the lithographic apparatus since the debris could seriously impair or contaminate optical components of the apparatus.
For example, the rotating contaminant trap can be provided with a driving mechanism to rotate the trap, and plates of the trap can have a rotational symmetry with respect to the rotation axis of the trap. It is desirable to rotate the trap with a generally high speed at which contaminant particles can be trapped efficiently, wherein the rotating contaminant trap can achieve long operational periods without requiring much maintenance.